Example embodiments of the inventive concepts relate to an operation method of an image sensor and/or apparatuses including the same, and more particularly, to an image sensor including a pixel array, which includes a color pixel, a depth pixel and a thermal pixel, an operation method thereof, and/or apparatuses having the same.
An image sensor is a device converting an optical image into an electrical signal. Recently, the computer and communication industries are developing demands for an image sensor having an improved performance in various devices such as a digital camera, a camcorder, a personal communication system (PCS), a game device, a security camera, a medical micro-camera, a robot, etc.
To acquire a three-dimensional image using an image sensor, information on depth or distance between a target object and an image sensor as well as information on color is required. A method of getting information on the distance between the target object and the image sensor may be generally divided into an active method and a passive method.
There are a time-of-flight (TOF) method and a triangulation method in an active method. A TOF method detects a phase change of an emitted light when the emitted light having a modulated waveform is reflected and returned from a target object. Here, the phase change may be calculated by an amount of charges occurred in a photoelectric element like a photo diode included in a depth pixel array.
A triangulation method senses a light emitted by a light source, e.g., a laser, at a fixed distance from an image sensor and reflected by a target object, and calculates a distance between the target object and the image sensor by triangulating a sensing result where a distance between the image sensor and the light source is already known.
A passive method calculates a distance between a target object and an image sensor by only using image information of the target object and without emitting a light to the target object. A stereo camera is a representative example where the passive method is applied.
A method of determining a thermal image of an object may include a bolometric technique and a photo detection element technique. In a bolometric technique, an electrical resistance of a bolometer is changed by heat of an object. The electrical resistance may change linearly in proportion to temperature of the object. A photo detection element technique detects a change of an amount of charges occurring in a photo detection element as the photo detection element absorbs an electromagnetic wave produced by heat of an object. Intensity of a thermal signal may decrease in inverse proportion to the square of a distance to an object.